If you have a bee nest facing a 1x1 area with flowering azalea as a floor (for the bees to collect pollen from) and glass on the left, right, and above, then the bees get stuck. Not all of them, but usually 1-2 per 1x1 area. This results in bees that have collected pollen but just sit there partially inside the glass and never returning to their hive. So if you have a hive with 3 bees, only 1 or 2 or in some cases none of the bees will be working.